a place for consciousness probing the deep structure of the natural world nov 2004

If physics is all structure, it is natural to suppose that in-trinsic properties related to the intrinsic properties we experience in conscious-ness are the intrinsic content of the phys

A Place for Consciousness: Probing the Deep Structure

of the Natural World

Gregg Rosenberg

OXFORD UNIVERSITY PRESS

Self Expressions

Minds, Morals, and the Meaning of Life

Owen Flanagan

The Conscious Mind

In Search of a Fundamental Theory David J Chalmers

Deconstructing the Mind

Stephen P Stich

The Human Animal

Personal Identity without Psychology

Eric Olson

Minds and Bodies

Philosophers and Their Ideas

Thinking without Words

José Luis Bermúdez

Identifying the Mind

Selected Papers of U T Place Edited by George Graham and Elizabeth R Valentine

Three Faces of Desire

Timothy Schroeder

Gut Reactions

A Perceptual Theory of Emotion

Jesse J Prinz

A Place for Consciousness

Probing the Deep Structure of the Natural World

Gregg Rosenberg

Series Editor

David J Chalmers, University of Arizona

A Place for Consciousness

Probing the Deep Structure

of the Natural World

Gregg Rosenberg

1

2004

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Rosenberg, Gregg.

A place for consciousness : probing the deep structure of the natural world / Gregg Rosenberg.

p cm.—(Philosophy of mind series) Includes bibliographical references and index.

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1 Consciousness 2 Philosophy of nature I Title II Series.

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expressed scientifically?

—Hedwig Born to Albert Einstein Yes, it would be possible, but it would make no sense It would be description without meaning, as

if you described a Beethoven symphony as a variation of wave pressure.

—Einstein’s reply

Donald Rosenberg, and my good friend David Han.

I loved you both Rest in peace.

My intention in writing this book was to create something whose importance liesbeyond the details of its arguments I myself consider this primarily a book of

ideas Of all my hopes, my dearest is this: that A Place for Consciousness should

provide inspiration to those like me who were raised with the physicalist doxy, accepting it but not fully comfortably, whose disquiet always has been si-

ortho-lenced at the end by the baffling question: How could it be otherwise? I believe

this book points to a place in the space of philosophical ideas where somethingtruly new and interesting exists I am, above all, trying to lead readers to thatplace so that they can return without me to explore it on their own The space ofideas is a public space, after all, and these particular hidden woods can surely bemapped better than I have been able to map them

We all know that in some sense there is a ghost in the machine The question that grips us is, why? Why does consciousness even exist? What use has nature

for an experience machine? This book proposes a place for consciousness in ture The framework developed here is ambitious in its scope and detail: It tiesexperience into a theory of the categorical foundations of causation Scholarsshould see it as an attempt to make a substantial advance in the development of

na-Bertrand Russell’s Structural Realism by borrowing some inspiration from Alfred

North Whitehead’s process philosophy General readers can simply see it as an

attempt to explain the mystery of the soul Liberal Naturalism is my name for

views of this type

Both Russell and Whitehead argued that physical science reveals only a tural aspect to nature If physics is all structure, it is natural to suppose that in-trinsic properties related to the intrinsic properties we experience in conscious-ness are the intrinsic content of the physical This suggestion raises severalquestions: (1) Why should the intrinsic properties of a physical system be expe-riential? (2) Why do they exist above the level of the microphysical, where large-scale cognitive systems might experience macrolevel intrinsic content? (3) Whyshould they form a unity of the kind we are acquainted with in consciousness?and (4) Why should phenomenal content, as the intrinsic content of the physical,correspond so closely to the information structure within the brain? By consti-tutively linking experience and causation, I answer these questions from firstprinciples

struc-This may seem like an unlikely project because the two problems of sciousness and causation are each tough philosophical chestnuts individually It isnot clear that thumping them together will really help us crack them open I hope

con-to meet the burden of the project: con-to argue that they need con-to be treated con-togetherand to show, in a very concrete way, how they do go together To meet my obli-gations, I argue that physicalism is false, yet I also show how one can rejectphysicalism in a way that is perfectly compatible with physical science This is atough ledge to walk Accordingly, the aims I have for this work extend only tomotivating, introducing, explaining, and defending the overall framework, whileleaving detailed discussion of its applications to a sequel I divide my aims intoseveral levels of ambition even within these boundaries

At the first level of ambition, I wish to provoke Within the book, I defend a

group of ideas that are at odds with the physicalist orthodoxy within science andthe philosophy of mind I believe the framework I flesh out here should at leastmake physicalists uncomfortable by showing that a nonphysicalist theory neednot be supernatural, naturalistically untenable, unmotivated, or hopelessly vague.After reading it, no one should rest comfortably with any assumption that alter-native views to physicalism must lead to absurdity

At the next level of ambition, I hope to challenge Physicalism’s strongest

sup-port has been the widespread intuition that only physicalism can guarantee thecausal relevance of experience in an acceptable way A first challenge coming out

of this book is that, by explaining why physics is not a theory of causation, it isable to show vividly why the issue makes sense only against a detailed back-ground theory of causation We see, furthermore, that traditional fears about al-ternatives to physicalism are without support under at least one possible and sub-stantial view of causation, a view that seems compatible with physical science.Not only does experience turn out to have a place in the causal order on the Lib-

eral Naturalist view, but I also make a case on grounds completely independent

of the mind-body problem that something exactly like it, in its most mysterious

aspects, is required for causation to exist

A second challenge, one for those sympathetic with the project begun in thisbook, is to see whether the ideas here lead to fruitful avenues of research orwhether, instead, they lead down a dead end The book only presents a frame-work called the Theory of Natural Individuals This framework should provide anew perspective from which to understand nature and many open questions aboutapplying the framework remain at the end of this work These open questionspresent the possibility for an actual empirical and philosophical research pro-gram It is particularly important to discover the details about the physical condi-

tions that correspond to the existence of the things I call natural individuals in

the book

At a third level, I hope to actually convince Although I propose some unusual

ideas here, I take no shortcuts, and I accompany my proposals with substantive

discussion and argument Liberal Naturalism is currently a minority position,

but it at least has current precedents within philosophy, especially in the work

of philosophers such as David Chalmers, David Griffin, Daniel Stoljar, GalenStrawson, and Michael Lockwood

My more specific proposal, which I call the Theory of Natural Individuals,

in-volves experience directly in the fundamental causal character of the world Thismore specific proposal seems very radical when stated baldly, but I have notpulled a rabbit out of a hat: Nowhere in this book will the reader find a conjur-ing trick, a ploy of misdirection, or a wave of the hands I have tried to workwith acceptable rigor by generalizing on some fairly mundane intuitions aboutthe world and about consciousness And I have tried, always, to respect science

I hope that I have succeeded in rationally motivating my case and that the work

is potentially fruitful

As a work of philosophical literature, A Place for Consciousness began in

1988 while I was pursuing my master’s degree in Artificial Intelligence I workedrather doggedly at trying to map the terrain for nearly ten years, resulting in atoo-rough first attempt at putting it all together in my 1997 dissertation inphilosophy and cognitive science The year before that, David Chalmers released

his book The Conscious Mind As I set about trying to tame the wild threads of

my dissertation work into something mature and more polished, I initially ceived of this book as a kind of unauthorized sequel to David’s book In time, Irealized that he had set the bar too high for me I hope instead to have produced

con-at least worthwhile companion reading

While this book is by no means an easy read, I have aimed to make it ble and interesting to the generally educated and intellectual public, even to thosewho have little or no training specifically in philosophy (with the exceptions ofchapters 3 and 10, which are necessarily technical) Although the book is long, it

accessi-is possible to take a short tour and still come away with the main ideas For thoseinterested in the short tour, I recommend reading chapters 1 and 2 to understandthe setup of the problem From there, skip to chapters 4, 9, and 12 If the shorttour piques your interest, go back and read the rest Those with a philosophicalbackground who are comfortable with one or more of the standard responses tothe antiphysicalist arguments should read chapter 3 Also, the remaining chapters

in Part I provide more thorough reasons than the short tour does for believingthat someone interested in understanding consciousness should look hard at cau-sation itself Finally, Part II may be interesting independently of one’s views onthe mind-body problem, especially the arguments against Humean views in chap-ter 8 and the detailed treatment of the causal nexus in chapters 9 through 11

Reinventing nature is hard work I could not have done even the little bit of itthat I do here without a lot of support from others, both intellectually and emo-tionally In my lifetime, my interests have taken me down many paths Each part

of me has found some reflection in this book, and I am indebted to many whohelped to steer me down my long and winding road

I thank Anthony Nemetz for first introducing me to the world of intellectualquestioning when I was an undergraduate business major His demanding elo-quence was a revelation to me at that time in my life, as nothing in my back-ground had previously exposed me to intellectual life

I owe my deepest debts from my time at the University of Georgia to DonaldNute Not only did he direct my master’s thesis when I was studying Artificial In-telligence there, but he has encouraged and supported me every step of the waysince: first in my decision to move into philosophy, then by encouraging me to go

to Indiana University to do my Ph.D., and finally by accepting me back at the Artificial Intelligence Center as a postdoctoral researcher

I thank Ned Block for the helpful conversations we had during my time atMIT in 1991 His insistence that ideas as unusual as mine need to be verystrongly motivated has always stuck with me, acting as a burr whenever I havebeen tempted to cut corners in my writing or thinking

I thank Douglas Hofstadter, whose books Metamagical Themas and Gödel, Escher, and Bach serendipitously fell into my hands while I was an undergradu-

ate, steering me toward the philosophy of mind and cognitive science My tual interactions with him while pursuing my Ph.D at Indiana University werechallenging and provocative

even-When I began my graduate work at Indiana University, I came to school vinced about the explanatory gap between the facts of consciousness and thephysical facts, and I suspected that there must be a deep link between conscious-ness and causation itself I was extremely fortunate to arrive there at the sametime at which David Chalmers was finishing his dissertation on consciousness inthe same program I have since discovered that the only thing comparable toDavid’s intellect is his generosity of spirit First, I thank David for clearing a paththat has made a book such as this one possible Second and most importantly, I

con-thank David for his friendship, for our many conversations and correspondences,and for his continued assurance that this work is interesting and worthwhile Fi-nally, I thank him for especially helpful comments on how to best organize thematerial in chapters 2 and 3 If I had always listened, then I am sure those chap-ters would be better.

These ideas were first written in preliminary form as my dissertation in ana University’s Philosophy and Cognitive Science program Mike Dunn chaired

Indi-my dissertation committee and gave generously of his time and advice Our versations ranged freely around the philosophical world, from topics such as Pla-tonism to the nature of properties to the nature of implication to the nature ofmind His restraint in passing harsh judgment on my speculations, choosing in-stead to ensure that I asked myself the right questions, made me feel that I had aright to travel over the wide terrain I cover in this book I thank him for provid-ing his comments and support at such a crucial time

con-I give special thanks to Anil Gupta, not only for the helpful discussions wehave had over the years but also for providing me with a role model for the way

a true philosopher should conduct himself His probity, patience, gentleness, and integrity have been an inspiration to me I thank Tim O’Connor for his en-thusiasm, incredible energy, and time at our long lunches His ideas on how to

do metaphysics seriously have been invaluable In my last year at Indiana, I was very fortunate to meet Brian Cantwell Smith Like me, Brian is a computerscientist-cum-philosopher, and the perspective that gives is difficult to put intowords I am grateful to Brian for the long hours he gave trying to help me im-prove my writing

I also thank John Gregg for supportive encouragement and extremely helpfulfeedback on drafts of this book John is owed a special round of thanks becausethe effort he put into commenting on a draft of this book chapter by chapter re-sulted in some substantial improvements in clarity William Seager and Torin Alter also took the time to read the entire work in manuscript form and providedmuch-needed feedback and support I also owe thank-you’s to Brie Gertler andBrad Thompson for helpful comments on parts of chapter 3

Nothing can substitute for heated arguments over beer that last late into thenight I have almost too many of these informal debts to list, mostly to my fel-low graduate students while I was in the philosophy department at Indiana University I would like to single out for special thanks a handful who have pro-vided especially memorable philosophical conversation: Tony Chemero, Diar-muid Crowley, Stephen Crowley, Eric Dalton, Craig DeLancey, Jim Hardy,Anand Rangarajan, and Adam Kovach

I owe my warmest thank-you’s to Leslie Gabriele Not only has she provided

me with an important intellectual sounding board, but also her friendship andsupport were priceless on a personal level I would not have gotten through some

of the rougher times over the past few years without her

Along those same lines, I would like to thank my long-time friends, especiallyAllen Domenico, Scott Davis, and Bob Lauth, for their support and encourage-

ment The most precious friendships are the ones that you know will last a lifetime.

My deepest thanks are reserved for my mother, Sally, my late father, Donald,and my brother, Alan They have made an investment in my life and identity that

is truly staggering to consider Every word in here reflects their love

The bulk of the writing of this book occurred in three bursts, enabled by port from outside sources In 1996–1997, I first formulated the basic ideas ex-pressed here as my dissertation, and I could not have done nearly what I didwithout dissertation-year support from the Nelson Foundation and the Institutefor Humane Studies In 1998–1999, I was able to advance the ideas in my dis-sertation and produce a first draft of the book while a Fetzer Fellow, and I thankthe Fetzer Foundation for their confidence in my work I thank the University ofGeorgia’s Artificial Intelligence Center for providing a supportive environmentwhile I was a Fetzer Fellow The book was stabilized and made ready for publi-cation in 2001, after I had the good fortune of selling my Internet security com-pany, and I am grateful for the free time I have had since

sup-Finally, none of the people to whom I owe these debts are responsible for anyerrors in fact, scholarship, judgment, omission, or organization in this book Iclaim its shortcomings all for my own

1 A Place for Consciousness 3

2 The Argument against Physicalism 13

3 Physicalist Responses to the Argument

against Physicalism 31

4 The Boundary Problem for Experiencing Subjects 77

5 On the Possibility of Panexperientialism 91

6 On the Probability of Panexperientialism 104

7 Paradoxes for Liberal Naturalism 114

9 The Theory of Causal Significance 141

10 A Tutorial on Causal Significance 184

11 Is Connectivity Entailed by the Physical? 218

12 The Carrier Theory of Causation 230

13 The Consciousness Hypothesis 248

PART I

Liberal Naturalism

disci-Consciousness is an ambiguous term1and not all senses of the term pose thesame kinds of problems The central problem it poses is where in nature to place

subjective experience, which is responsible for the subjective quality of our tence Philosophers call this sense of consciousness phenomenal consciousness.

exis-Phenomenal consciousness is special It is different from just wakefulness, for stance Dreaming is a way of experiencing, and, therefore, in the sense that needsplacement, we are conscious during sleep

in-Phenomenal consciousness is not necessarily consciousness of anything else.

For example, when I close my eyes and cover my eyelids with the palms of myhands, I see diffuse shapes floating in the blackness and jumpy patches of dilutedcolor These are experiences and are thus elements of phenomenal consciousness,

even though they do not seem to represent anything.

Phenomenal consciousness does not necessarily involve language or understanding For example, when a newborn infant cries on first experiencing

self-the world, it must be feeling something, even though it has not yet developed

lan-guage or self-understanding Because it feels, it is phenomenally conscious

We identify phenomenal consciousness by being acquainted with it, not bylooking up a scientific definition Even though “phenomenal consciousness” doesnot have a scientific definition yet, I mean phenomenal consciousness when I use

the word consciousness in this book If we need a definition, the best we can do

is to create an operational definition by calling attention to it in increasing levels

of detail

The most succinct way to convey the meaning of the term is through ThomasNagel’s popular phrasing from 1974: A creature’s subjective experience consti-

tutes what it is like to be that creature For example, part of what it is like to be

a person with normal color vision is for purple things to subjectively appear in acertain way, as having a certain kind of visual quality to that person Purple sub-jectively appears different from pink, which is subjectively different from orange,which is subjectively different from black, and so on Together, the subjective ap-

pearances of these qualities help make up what it is like to be a person with

nor-mal color vision

After becoming aware of these visual qualities as qualities, you may naturally wonder what the colors from a larger color space look like For example, some

birds can see colors that no person can see What is the experience like whenthese birds see the extra colors available to them? Once you know about theirability, a question about the character of their conscious experience remains Thefacts about these birds’ phenomenal consciousness include what it is like forthem to see the extra colors they see

Similarly, just as the subjective qualities involved in seeing something (e.g.,colors, shape, and depth) are different in kind from the ones involved in hearingsomething (e.g., tone, pitch, and rhythm), there must be a set of distinct qualitiesthat make up what it is like for a bat using its echolocation Are the qualities thatthe bat experiences like those you experience when seeing something, or are theylike those you experience when hearing something, or are they like somethingelse altogether? In the same spirit, you may also wonder what the qualities andsensations associated with a manta ray’s sensing of electromagnetic currents onthe ocean floor are like for the manta ray

Examples multiply easily Philosophers call the subjective qualities these

ques-tions point to phenomenal qualities, or qualia At the extreme, you may even wonder, however implausibly, whether it is like anything at all to be these crea-

tures Perhaps they are unconscious robots, all “dark inside,” without any qualia

at all.2

Phenomenal consciousness is richly varied, complex, and subtle For example,the exact organization of the qualities of experience, and perhaps even their char-acter, seems to be very responsive to conceptualization An example of this oc-curs when we stare at visually ambiguous figures such as the Necker cube in fig-

ure 1.1: The qualitative experiences associated with seeing its face as oriented upward or as oriented downward are very distinct This suggests a location for

the world’s repository of facts concerning phenomenal consciousness For a ticular creature, the facts concerning what it is like to be that creature are consti-tuted by (1) its capacities for experiencing phenomenal qualities in the first per-son and (2) its way of conceptualizing the world.3

par-What is the place of consciousness in our world? From where does nal information come? Are phenomenal facts ordinary physical facts? Are they

phenome-the kinds of facts that ordinary physical facts can form a basis for? And, if so, inwhat way can physical facts provide a basis for them? We do not have good an-swers to these questions yet.

Moving just slightly beyond Nagel’s slogan, Brian Loar (1990) delivers alonger description of the intended target by concisely expanding the slogan, What

it is like to be:

On a natural view of ourselves, we introspectively discriminate our own ences and thereby form conceptions of their qualities, both salient and subtle These discriminations are of various degrees of generality, from small differences in tac- tual color experience to broad differences of sensory modality, e.g those among smell, hearing and pain What we apparently discern are ways experiences differ and resemble each other in respect of what it is like to have them Following com- mon usage, I will call those experiential resemblances phenomenal qualities; and the conceptions we have of them, phenomenal concepts Phenomenal concepts are formed “from one’s own case” They are type-demonstratives that derive their reference from a first-person perspective: “that type of sensation”, “that feature of visual experience” And so third-person ascriptions of phenomenal qualities are pro- jective ascriptions of what one has grasped in one’s own case: “she has an experi- ence of that type.”

experi-I want to clarify Loar’s characterization in one important respect Rather than

using phenomenal qualities to denote resemblance between experiences, I use the phrase to denote the qualities within experience that are responsible for these re-

semblances between them

At the next level of detail, you can catalogue varieties of phenomenal ence by paying close attention to the different kinds of experiences you can have.Cataloguing exercises can direct and refine your awareness of the subject matter

experi-by highlighting for you your own subjective acquaintance with the characters ofyour inner life David Chalmers catalogues experience in the first chapter of his

The Conscious Mind (1996) He calls attention to, and gives short accounts of,

the fascinating variety of phenomenal content found in experiences as diverse

Figure 1.1 A Necker cube When we stare at the Necker cube, our phenomenal experience changes depending on whether we perceive it as facing upward or downward.

as: visual, auditory, tactile, olfactory, and taste experiences; experiences of perature; pains; other kinematic and proprioceptive sensations; mental imagery;conscious thought; emotions; and the sense of self When thoughtfully done, catalogues vividly create awareness of phenomenal consciousness and its manyelements and forms.

tem-At the most extreme level of detail, you can isolate the meaning of nal consciousness by comparing and contrasting it with other senses of the term consciousness Ned Block (1995) does this in a concise way by comparing and

phenome-contrasting “consciousness” in the sense of having cognitive access to

informa-tion with “consciousness” as experience Charles Siewert’s (1998) The cance of Consciousness contains an extremely detailed attempt to isolate the

Signifi-sense of the term that picks out the mystery, drawing it out from its hiding placeamong the other senses of the term

1.2 The Mind-Body Problem

If you want to understand the problem, Descartes is a good place to start RenéDescartes is often credited with creating the modern form of the question, What

is the relationship between the mind and the body? This is the mind-body problem.

Descartes believed in a metaphysics of substance and properties A substance

is supposed to be the metaphysical substrate that supports the existence of

prop-erties Properties are repeatable characteristics of things, in the sense that many

different things can have the same property For instance, mass is a property, asmany different things can have mass

Descartes proposed that the substance matter essentially has properties of tial extension and causal power He also believed that the mind is a substance and

spa-that it essentially has the properties necessary for rationality and causal power.Beyond this, Descartes believed that rationality was inessential to matter, thatspatial extension was inessential to mind, and that, because they have differentessential properties, matter and mind could not be the same substance This is

called substance dualism.

Substance dualism raises a question about creatures like us who have both

minds (composed of the rational substance Descartes called mind) and bodies (composed of the spatial substance Descartes called matter) How are these sub-

stances, which are so different, brought together to be a person?

Descartes suggested that they interact with one another through the brain He

admitted to not really understanding how this occurs, but he believed that it must

occur Today we call that position interactionist dualism Together, Descartes’s positions made him an interactionist substance dualist.

Not many philosophers or scientists today believe in interactionist substancedualism Most philosophers and scientists believe that mental activity is physi-cally constituted by brain activity Among academic scientists and philosophers,

the most commonly held position is now physicalism, which holds that

every-thing is physical in some sense Physicalism is basically the position you would expect to be called materialism, except without the historical commitment to the

existence of a material substance In place of Descartes’s substances, physicalismjust commits itself to the existence of the basic physical properties and events,whatever they turn out to be

Physicalism belongs to the branch of metaphysics called ontology Ontology is

the study of what kinds of things exist, with particular emphasis on the different

ways of existing possessed by different kinds of things For example, hurricanes,

speed limits, bosons, moral values, numbers, and minds all exist.4On their faces, at least, these all seem to be very different sorts of things, each with itsown unique nature and way of existing

sur-Ontologists generally focus on two kinds of questions First, what is the nature

of these things? Second, how do all these diverse things come together so thatthey are able to exist in the same world? Philosophers usually answer this second

kind of question by proposing fundamental categories of properties, objects,

events, or processes whose existence they can see as grounding the existence of

other kinds of things By fundamental, philosophers mean that these are the

things from which the existence of every other thing is derived

If one is religious, one may hold that this fundamental thing is God If onewants a more scientific hypothesis, however, one needs to find another category

of things to do this job That is where physicalism steps in Physicalism is the

thesis that all other kinds of things wholly derive their existence from the

exis-tence of the physical Among these other kinds of things are hurricanes, speed

limits, moral values, numbers, and, most important in this book, consciousminds

Physicalists often charge Descartes with serious errors that still infect ourthinking about the mind I argue that Descartes’s most dangerous errors were theones he made about matter, not mind Descartes felt forced to his dualism chieflybecause the science of his time had revolutionized our ideas about matter After

the scientific revolution, people thought of matter as something primarily tative and geometrical and best described in terms of how these quantitative

quanti-states vary at different points in space and time Thus mathematics and geometry,rather than perception and sensation, came to provide the best models for under-standing the essential nature of matter This revolution in thinking was as radicaland important as any intellectual revolution has ever been I believe it is hard for

us now to fully appreciate it

Prior to this revolution, in which Descartes himself was a leading figure,

edu-cated people had primarily thought of matter as something qualitative Qualities

are attributes, not necessarily quantitative, found in sensations that make eachkind of sensation fundamentally unlike the other kinds For example, the distinctfeelings of itches are qualities and are different from the qualities of smells Al-though found in sensations, qualities were thought to exist in matter quite gener-ally, whether sensed or not Common opinion was that matter is best understood

by proposing qualities and investigating how these qualities are qualified or

con-ditioned through intimate causal relationships that bind them to one another and give them form.

This pivotal shift from thinking about matter as something qualitative to ing about it as something quantitative drew a revolutionary line that has sharplydifferentiated modern from premodern thinking In this book, I argue thatDescartes’s error, and the error that still haunts us, is that we have come to be-

think-lieve that this revolutionary view of matter is all there is to matter

As revealed from a fundamentally Cartesian perspective on the physical, thehuman body is a marvel whose subtlety, flexibility, and complexity uplift the

word machine Natural science tells us that the body is made ultimately of very

tiny and exotic physical entities, and we know that it consists in the motions of,and interactions among, delicately layered physical structures Our bodies arespatiotemporal organizations of these tiny entities, driven by an enormous num-ber of microphysical interactions

From this perspective, the mind-body problem arises immediately: How could

a collection, any collection, of microphysical interactions have macrolevel riences? According to physical theory, the entire being of these microphysical en-

expe-tities consists in the quantitative dispositions that produce their intrinsic ics and their intimate couplings The mystery of consciousness is the question of

dynam-why this assembly, this whirlwind of causation, should ever feel Couldn’t this

causation go on without feeling, without sensation, without experiencing at all?Viewed in the large, these finely layered patterns are dynamical wonders, but it ishard not to wonder why the dynamics should be conscious Physical causationproduces changes in quantity, shape, and motion, but why should a congeries ofquantity in motion, however complexly shaped, ever experience the delightfulsweetness of cheesecake? Questions such as this pose the greatest obstacle to thechallenge of naturalizing the mind

1.3 Liberal Naturalism

Even though I argue against physicalism, I am a naturalist The view I favor is

Liberal Naturalism I view naturalism as a methodological requirement to placehuman beings in the world without making special, ad hoc assumptions that arediscontinuous with everything else we have good reason to believe about nature Afundamental message of this book is that we have good reasons, reasons independ-ent of mind, to understand nature differently than physicalists typically do, and Ipropose a specific way of doing it that allows us to find a place for consciousness.The position I develop is a kind of dual-aspect view that I think respects what

is right about the intuitions of both physicalists and substance dualists aspect views provide an alternative to substance dualisms for antiphysicalists.Whereas substance dualism proposes that there are two fundamentally differentand potentially independent kinds of entities, matter and mind, dual-aspect viewshold that there is one fundamental kind of entity but that this entity has morethan a physical aspect It is like the difference between thinking the evening star

Dual-and the morning star are different stars Dual-and thinking that they present differentaspects of the same thing, the planet Venus

Like physicalism, Liberal Naturalism holds that the world is probably posed from a single fundamental kind of thing This fundamental kind of thing,

com-if it exists, probably has a set of fundamental properties that are mutually related

in a coherent and natural way by a single set of fundamental laws However, likesubstance dualism, Liberal Naturalism holds that some of these properties andlaws are not physical properties and laws What ties the physical and nonphysi-cal together is a deeper kind of thing of which they are both aspects

As a Liberal Naturalist, I identify (to a greater or lesser degree) with DavidChalmers, Thomas Nagel in some of his moods (e.g., his 1998 work), WilfridSellars on some ways of reading his work (e.g., his distinction between his physicalism1and physicalism2), Abner Shimony, Grover Maxwell in his writings

on structural realism (1971, 1979), Michael Lockwood, Alfred North Whitehead,

David Ray Griffin, and Bertrand Russell in his neutral monist phase The LiberalNaturalists recognize the possibility that the specifications of physics and whatcould subsist in a world wholly portrayed by physics may not circumscribe na-ture’s limits That allows the Liberal Naturalist to step comfortably outside thestandard physicalist ontology while retaining a naturalist outlook

The positive project in this book is to identify what these nonphysical ties are; to explain why they should exist; and to give reasons for believing they

proper-fit cohesively within a scientific and naturalistic worldview I pursue these goals

by introducing a substantive view of causation This metaphysically rich picture

of causation provides the bridge that takes us from the physical to consciousness

It also respects the causal closure of the physical, as I attempt to complete ourview of causation by adding elements that are complementary to the structure ofactivity described by physical science and that, for that reason, are every bit asessential to it as is the physical

I make and develop several distinctions between aspects of causation, including:

1 Distinguishing the effective properties as properties that give individuals

the inherent potential to place constraints on one another

2 Developing a theory of shared receptivity to provide a context in which

the effective properties can be realized and do their work, thus forming

the basis of the connectivity between individuals.

3 Proposing that the effective and receptive causal dispositions must be

carried by fundamental intrinsic properties It is through understanding

these carriers that we can understand why consciousness exists

After developing this model, I argue that physics describes only ral patterns in the appearances and values of effective properties I argue that arealist account of the causal nexus goes beyond this physical aspect becausephysical theory leaves out information about receptive connectivity and the in-trinsic carriers It follows that a complete theory of the causal nexus needs to gobeyond physical theory

spatiotempo-If the model I propose and develop in this book is right, experiencing is a damental element of nature It has a natural place in the implementation of cau-sation, and phenomenal qualities implement nature’s effective constraints In theterminology I introduce later, experiencing acts as an intrinsic carrier for causa-tion itself The phenomenal qualities carry the effective properties of individualswithin a causal nexus, and the experiencing of these qualities carries the recep-tiveness had by members of the nexus to these effective properties.

fun-It turns out that the place of consciousness in the natural world intrinsicallyconnects it to a larger, metaphysical background via its intimacy with causationitself Under the kind of realist account of causation I detail, a picture emergesthat does not drive a wedge between consciousness and the physical world In-stead, it locates us within a world that is richer both naturally and metaphysicallythan the one previously available The resulting view avoids the interaction ofDescartes’s substance dualism without slipping into the brute and inexplicableidentities of physicalism, and so provides the foundations for a possible LiberalNaturalism

1.4 The Structure of the Book

The main body of the book is divided into two parts In part I, “Liberal ism,” I first argue that physicalism cannot adequately account for consciousness

Natural-To establish physicalism’s failure, I analyze what it means to be a physical fact

by establishing an analogy with an artificial kind of world The analysis shows,

in a concrete way, why no physicalistic theory will entail the facts of ness and defends the importance of entailment to the truth of physicalism Thefailure of physicalism creates a puzzle regarding just what consciousness might

conscious-be, if not physical

After presenting this puzzle, I explore problems and tensions created by the

implication that there must exist fundamental nonphysical properties How can the world have both physical and phenomenal aspects? And why would it? By

searching the places at which these two aspects seem most incompatible witheach other, I try to discover clues about where the incompleteness in our knowl-edge might lie Among other conclusions, I argue that the existence of con-sciousness is evidence for hidden structure within nature Also, I argue that, atevery turn, our search points us toward the need to more fully understand causa-tion itself

Perhaps the metaphysics of causation is richer than materialists usually pose I devote part II of the book, “Faces of Causation,” to a direct analysis ofcausation and the conditions on the possibility of causal interaction As a firstpoint, I build a case that the explanation of causation also requires nature to havemultiple aspects: its effective aspect, its intrinsic connectivity, and the intrinsiccarriers of the causal dispositions I build a speculative metaphysics for causa-tion, a metaphysics in which the roles of each type of element are specified in arigorous way The detail of my development allows me to place consciousness in

sup-the world in a way that answers sup-the puzzles, paradoxes, and tensions I raise inpart I while avoiding the usual objections to dualist views.

1.5 The Sliding Tile Puzzle

The mystery of consciousness is both profound and exciting If one thinks hardand long about it, the questions it raises will linger and endlessly deepen Even-tually, they seem to transcend specific questions about consciousness, touchinginsecurities about our understanding of nature herself At first one tries to solvethe puzzle as though it were a jigsaw puzzle, with pieces nestled stably in theirproper places Eventually one begins to realize that, to solve the puzzle of con-scious experience, we may have to view the project as being more like trying tosolve a sliding tile puzzle, such as the one in figure 1.2

A sliding tile puzzle consists of a rectangular frame with movable tiles within

it, each tile decorated with a different part of the puzzle Initially, the tiles arescrambled, and the goal is to unscramble them to retrieve the puzzle’s picture.The rectangle contains one empty space, and the puzzle solver must rearrange the

Figure 1.2 Understanding how the pieces of nature fit together is sometimes

like trying to solve a sliding tile puzzle.

tiles by sliding them into and out of this empty space By repeating this, the zle solver hopes to undress the confusion and reveal the puzzle’s ornamentalface.

puz-Sliding tile puzzles contain a trap, a seductive property that lures the

unsus-pecting Often the puzzle solver can bring order to almost the whole puzzle,

per-haps fitting every piece into its proper slot except the last two tiles These lasttiles might be transposed, for instance, each in the other’s slots The trap issprung when the puzzle solver holds stubbornly to the hard-won order in the rest

of the puzzle, afraid that disturbing it too much will cause it to disappear, never

to return Seduced by the order already in the puzzle, the puzzle solver searchesdesperately for a minimally disruptive solution, one that places the pieces with-out disturbing the rest of the puzzle very much

Unfortunately, the puzzle solver cannot usually solve the tile puzzle this way

To fit the final pieces in place, one has to regress first and then rebuild the old der from a new direction The trap is that, because the puzzle solver flinches atevery challenge to the old order, the ideal of completing the puzzle becomes ahopelessly elusive goal The irony is that the hard-won old order would eventu-ally reappear within a more completely ordered context, if only the puzzle solvercould find the strength to first challenge it and, temporarily, relinquish it

or-In writing this book, I have approached the problems of consciousness andcausation as though they are the final two pieces in a sliding tile puzzle I wish

to help put them into their proper places within a naturalist framework, and I lieve that sound arguments exist that this achievement will carry a cost This costwill require temporarily reneging on some of the hard-won order that science hasbrought to our understanding of nature The cost is this: We must concede thatphysicalism is an inadequate version of naturalism To justify this cost, I have totouch many other tiles With luck, the richness of the puzzle will serve to makethe effort worth the investment

be-The Argument against Physicalism

2.1 Introduction

Physicalism says that the fundamental physical facts are the only fundamentalfacts All other facts, whether about rocks, tables, morals, or minds, are deriva-tive on these physical facts In this chapter, I argue that physicalism is false byarguing that a purely physical world could not contain facts of experience Oth-ers have given arguments of this kind, but I hope to look at this kind of argument

in a fresh way In chapter 3 I defend the argument against objections

My argument is not a form of conceivability argument or knowledge argument

It is a direct argument that the phenomenal facts are of a type that cannot be tailed, either a priori or a posteriori,1by the physical facts To diagnose preciselywhy entailment fails, I produce a working analysis of physical facts as a type.This working analysis is central to this chapter, and it recurs in part II Becausethe specific lessons of this chapter’s argument hold recurring importance, I askeven readers who are familiar (or impatient) with the debate over physicalism topay some attention to this chapter

en-2.2 The Dialectic

Recent antiphysicalist arguments rely on thought experiments that claim to showlimits on the physicalist program for explanation and, by implication, the meta-physical status of physicalism In his seminal paper, “What Is It Like to Be aBat?” (1974), Thomas Nagel argues that any physicalist account of the universe,

by being inherently objective, will leave out the subjectivity of points of view.Nagel argues that this omission is reflected in the fact that even when we knowall about the physiology of creatures that are very different from us, we do notknow what it is like to be them

Among others, Frank Jackson (1982) and David Chalmers (1996) have refined

Nagel’s guiding intuitions In Jackson’s well-known Knowledge Argument, heasks that we consider a superneuroscientist named Mary From within a black-and-white room, through books and observation of a black-and-white TV, Marylearns everything there is to know about the functioning of the visual system.Jackson maintains that, nevertheless, Mary learns something the first time she isexposed to color She learns what the experience of blue is like, for instance.Jackson claims that it follows that physicalism must be false because we can

know all the physical facts without being able to know, even in principle, all the

facts

Chalmers’s Conceivability Argument asks us to conceive of a universe cally identical to ours from Big Bang to Big Crunch, but with the twist that ourcounterparts have no conscious mental life They are subjective zombies.Chalmers argues that such a universe is conceivable and, furthermore, meta-physically possible He argues that this shows the falsity of physicalism by show-ing that the facts about qualitative consciousness are further facts, not determined

physi-in the appropriate way by the physical facts

By using thought experiments, the antiphysicalists aim to show that there is no

entailment from physical facts to facts about experience, where an entailment is understood as an a priori implication (A a priori entails B if one can rule out a priori that A is true and B is false) That is, they aim to show that facts about ex-

perience cannot in principle be deduced from physical facts by a priori reasoning.From there, the antiphysicalists argue that physicalism is false Later I argueagainst entailment in a different and more general way, using an analogy to an ar-tificial world with a toylike physics This analogy allows us to diagnose exactlywhy no kind of entailment, either a priori or a posteriori, can hold in the realworld The result is a direct argument against entailment that does not rely on aconceivability claim or the knowledge argument

2.3 The Game of Life

Cellular automata names a certain class of artificial, digital worlds A cellular

au-tomaton consists of points, or “cells,” located in an abstract space, all of whichcan have kinds of “causal” properties Computer modelers define various physicsfor these worlds and study the behaviors they exhibit To start an automaton, oneassigns an initial distribution of causal properties to the cells, perhaps at random.The automaton then evolves, changing states according to rules that apply point-wise to the space Typically, the rules that determine which properties a cell willhave at a given time are a function on the properties of neighboring cells at animmediately preceding time One then studies what kinds of entities can evolveand what sorts of properties these entities can have, given the physics that themodeler has created

Life is the name of a kind of cellular automaton that evolves on a sional grid The Life world has been used in discussion of the mind-body prob-

two-dimen-lem before, most notably in Dennett (1991a), and its physics is extremely simple

and easy to understand For these reasons, I am also going to use the Life world

as my example cellular automaton I define a pure Life world as follows: Definition 2.1: A world is a pure Life world if, and only if, it is a Life world of

which no fundamental facts are true except those stipulated in its physics

In Life, we are supposed to think of each cell on the grid as a square and as

having eight neighbors: a neighbor touching it on each side and a neighbortouching it on each corner The location of a cell never changes Additionally, a

cell can host exactly one of two mutable causal properties, being on or being off,

at any given time step To illustrate the basic scheme, figure 2.1 depicts a cell and

its neighbors Three simple rules govern the evolution of a Life automaton:

1 If a cell has exactly two on neighbors, it maintains its property, on or off,

in the next time step

2 If a cell has exactly three on neighbors, it will be on in the next time step.

3 Otherwise, the cell will be off in the next time step.

Imagine a Life universe consisting of an infinite grid The two properties sessed by grid cells, on and off, are the basic physical properties in the Life uni-

pos-verse The rules governing the grid’s evolution are that universe’s laws of

physics When thought about in this way, Life becomes a good modeling ground

for understanding how physical facts can entail other kinds of facts

N2 N1

Despite its simple physics, the Life automaton can evidence a tremendous

va-riety of patterns For instance, John Conway, the mathematician who invented it,

proved that a Life grid can be a universal Turing machine.2More remarkably, hehas proven that the grid can support extremely complex patterns that are self-replicating in von Neumann’s sense of nontrivial self-replication (Poundstone1985) These patterns have functional properties similar to DNA and provide the

motivation for the name Life In general, it is the interesting patterns like these in Life that create entailments from its basic physical facts to facts of other kinds.

Entities called gliders serve as a simple example of how entailment works in

the Life universe A glider consists of a sequence of patterns, each containing

ex-actly five contiguous cells, which move across the grid in a characteristic fashion(see figure 2.2) Gliders make for a useful example because other cellular au-

tomata can also produce gliders This means that Life can present sufficient ditions for the existence of gliders but cannot present necessary conditions, so we cannot define the property of being a glider in terms of Life physics To be a

con-glider just means to have a certain structure and to evolve in a certain way, gardless of the underlying physics The glider structure produces a predictablerange of successive states that, lacking interference, move across the grid.Even before seeing what a stage in the glider pattern actually does when we

re-instantiate it in a Life world, we know that Life will allow for structure to arise

and for the evolution of those structures Seeing this, it then becomes obvious

that Life worlds (epistemically) might support conditions that entail the existence

of gliders To rule out the (epistemic) possibility that gliders could exist in a Life

universe, we would need a specific proof that the physics could not producethem

As it turns out, the Life physics can produce gliders One can prove this by taking a pure Life world, producing one of the configurations in the life cycle of

a glider, and checking that it evolves correctly over time It does, so we see that

Life worlds can entail the existence of gliders.3

In this example, entailment acts as a determination relation: The basic facts in

Life are the facts about the distribution of the “on” and “off” properties and how they redistribute over time Also, the basic Life facts necessitate the facts about

gliders without our having to introduce any new fundamental ontology Instead,the necessity is grounded in conceptual truths about what it means to be a glidercombined with the empirical truths about the configurations of the basic proper-

ties in the Life world and the evolution of those configurations Given a situation

in the Life world, these interpretive truths are enough to determine the truth of

facts about gliders.4

2.4 The Form of the Argument against Physicalism

With this understanding of the Life world in mind, the argument against

physi-calism that I defend is:

Figure 2.2 One full cycle of states in the existence of a glider Notice that the glider in figure (e) is a copy of the glider in figure (a), only moved up the grid by one cell.

1 Facts about a pure Life world do not entail facts about phenomenal

con-sciousness (either a priori or a posteriori)

2 If facts about a pure Life world do not entail facts about phenomenal

con-sciousness, then facts about a pure physical world do not entail factsabout phenomenal consciousness

3 Therefore, facts about a pure physical world do not entail facts aboutphenomenal consciousness

This is my overall argument By presenting it, I will lock onto a theoretical ception of what it means to be physical and to be entailed by the physical facts

con-My strategy is to use the physics of the Life world to draw out the categorical

structure of physical theories in general, identifying the kinds of informationphysical theories convey and exposing the kinds of conditions that make physicalproperties the kinds of properties they are

2.5 The Argument against Life Entailing Consciousness

Facts about a pure Life world do not entail facts about phenomenal ness I defend the first premise of my argument against physicalism by defending something that I call the Skeptic’s Claim The Skeptic’s Claim is that the facts about a pure Life universe cannot entail facts about consciousness The skeptic’s

conscious-use of “entail” includes both a priori and a posteriori entailment Thus we may

consistently acknowledge any kind of structure and functionality for Life objects and still deny the presence of consciousness in a Life universe The argument I

defend for the skeptic is:

1 The fundamental properties of a pure Life world consist of bare differences.

2 Facts about phenomenal consciousness include facts about qualitativecontent

3 Facts about bare difference cannot entail facts about qualitative content

4 Therefore, some facts about phenomenal consciousness are not entailed

by pure Life facts.

Premise 1: Pure Life worlds consist of bare differences What is a bare ence? I mean the phrase bare difference to express an intuitive idea that can be loosely explained by saying that Life’s physics leaves us in the dark about what

the “on” and “off” properties are themselves It just tells us that they are ent and enter into certain dynamic relations

differ-What is an “on” property? It is not the “off” property differ-What is the “off”

prop-erty? It is not the “on” property That, plus the rules of evolution, is all Life’s

physics specifies about the “on” and “off” properties In this way, bare ences are defined circularly in terms of their difference from each other More-

differ-over, if the Life world is pure, we know that there are just no other facts about

those properties because we know that the physics tells us everything there is to

know I say the difference is bare because it does not rest on any further

cate-gorical facts about the properties (if the world is pure) It is a difference that is

ungrounded by any further facts about internal structural differences betweenthose entities or internal relations of difference or contrast between unspecifiedstructureless intrinsic contents

Postulating facts about intrinsic natures in the Life world would violate the

pu-rity condition we are working under, because no facts about intrinsic natures are

specified by its physics Thus a Life world with any basis other than bare ence would be an impure Life world For now, I think the best way to conceive

differ-of a bare difference between two properties, x and y, is to think differ-of the relation

as primary rather than implied by other facts, with the existence of the relata,such as they are, derivative on their participation in an ungrounded relation ofdifference

Bare differences are difficult to conceive of Some readers may reject the idea

altogether, insisting that a Life world must have some kind of intrinsic basis.

With an intrinsic basis, there would be a contentful difference where the tence of the difference would be derivative on further facts of intrinsic differencebetween some unspecified natures of the relata It is clear, however, that suchfacts about an intrinsic basis would go beyond what is specified by the bare laws

exis-of the Life world I argue later that such an intrinsic basis is crucial to the

pro-duction of consciousness, but to presuppose it now would beg the question aboutwhether pure physics can specify an adequate basis for the world So I stay with

the “bare” understanding of Life for now and examine it more critically later in

the book

My defense of the Skeptic’s Claim begins with a closer look at the materials

available in the Life universe To reiterate: What does it mean to be an on or off

property? The only two requirements are that (1) they should be distinct and (2)they should be instantiated in patterns conforming to the rules set down by the

three dynamical laws In short, the distinction between being on or being off is a merely formal one On and off specify bare, content-free difference.

Because it specifies only bare difference, the Life specification is, at heart, a

structural schema for a universe It specifies certain patterns of contrast between

kinds of being, patterns that must hold for a universe to count as a Life universe.

As we ascend to higher levels of organization in the pure Life world, we do not escape from the circle of bare difference In pure Life we have a world poten-

tially consisting of a huge number of simple, bare differences lying side by side,

with reliable, regular transitions between them A Life structure is a pattern of

bare difference, mere contrast

Premise 2: Consciousness contains qualitative content. The skeptic claims that

we have observational knowledge that consciousness contains qualitative content,

involving what are often called qualia The claim that knowledge of qualitative

content is observable is critical to the force of the skeptic’s arguments Without

it, there is no strong reason to resist performing a modus tollens on the

conclu-sion, simply eliminating phenomenal consciousness and its troublesome qualitiesfrom our list of explanatory targets In the following I support the Skeptic’s

Claim by providing a direct argument that qualia are indeed observables By

call-ing qualia observables, I mean that they meet four conditions:

1 They belong to a type whose members are potential objects of awareness

2 We can become aware of them without the aid of special instruments

3 The dubitability of our belief in facts of the relevant type is almost zero

4 Our awareness of instances of the type is reliable

Some people do raise objections to the claim that qualia are observables (e.g.,Wilkes 1988; Dennett 1991b; Akins 1993) The most common worry is that mod-eling our knowledge of qualia on perception is misleading, so people are unsurehow we can be observing them Minimally, opponents sympathetic to theseeliminativist worries hold that the knowledge grounding the skeptic’s conclusions

is highly refined, theoretical, and corrigible

To these worries, the skeptic replies that the objector seems to have an sonably narrow concept of observation By insisting that something can achievethe status of an observable only if we obtain the information about it through or-dinary perception, the objector is making too strong a claim The objector rulesout of court a huge amount of information about consciousness that we have ac-cess to and that a theory of consciousness should have to explain I defend thefollowing argument that qualia are observables:

unrea-1 Some thoughts and memories are observables

2 If thoughts and memories are observable, then the evidence for them isobservable

3 Phenomenal contents (i.e., qualia) provide evidence for observable kinds

of thoughts and memories

4 Therefore, qualia are observable

As examples of observable thoughts and memories, here are two statementsthat most would agree express observable facts:

(A) Last night I thought about my childhood

(B) Sometimes I think about my childhood when no one else is around.The previously defined characteristics of observables allow facts such as (A)and (B) to attain the status of useful falsifiers for scientific and other theories Forexample, a theory of mind fails to account for some of our evidence about our-selves if it fails to account for how we can sometimes think about our childhoodswhen no one is around

Facts such as (A) and (B) are no more problematic than many other facts we count as observable Also, they are introspectively observable, and the fact that

perception does not mediate our awareness of them seems like a red herring

Ba-sically, if anything counts as observable, then (A) and (B) must count as

observ-able, too Our skeptic firmly insists that a science of mind must recognize servables such as these if it wants to be treated as legitimate Because facts such

ob-as (A) and (B) turn out to be no more problematic ob-as observables than are

per-ceptually mediated facts, a straightforward argument delivers the phenomenalqualities as observable also.

Last night, I lacked behavioral evidence that I was thinking about my childhood

I was not writing about it, nor talking about it, nor acting on it I was, in fact,scouring my bathtub How do I know what I was thinking about? What was the evidence of my thoughts? I introspectively observed my thoughts, and my evi-dence was the presence of certain kinds of conscious phenomenal imagery, verbal,imagistic, and kinematic: phenomenal images of childhood scenes, spoken andheard sounds, and remembered emotions That imagery may have been identical tothe thoughts or it may just be a concomitant of thinking that gives evidence forthoughts the way that snow on the ground gives evidence for cold weather

In either case, my awareness of the conscious phenomenal imagery cannot beconsidered more doubtful than my awareness of my thoughts Because the phe-nomenal imagery is the evidence for such thoughts, it is easy to argue that5thesentence (A) has the status of an observation claim only if the phenomenal im-agery that is my evidence for it has the status of being observable Similarly, I

obtain my knowledge of types of thoughts such as those referred to in sentence

(B) from observables only if I also obtain my knowledge of types of phenomenalqualities from observables

Arguments such as this, the skeptic maintains, establish that we obtain edge of what the phenomenal qualities (colors, feelings, sounds, imagery, othersensations) are like through observation For example, I obtain my knowledge ofwhat the shades of blue look like to me by consciously experiencing them Con-sequently, phenomenal qualities are observables (which is not to say observation

knowl-of them is always either easy or incorrigible) As scientists, we must hold nations and theories accountable for phenomenal information obtained throughobservation

expla-This conclusion does not cross David Lewis’s (1995) recommendation thatphysicalists must deny that we have special, unmediated access to the true nature

of qualia To possess phenomenal information, our skeptic does not need to have

a more direct access to qualia than to any other kind of observable The skeptic

is chiefly concerned with the character of the connection between phenomenal

qualities, as disclosed through the phenomenal information we do have available,

and their hidden natures, if they have hidden natures

Premise 3: Bare difference does not entail qualitative content. Could consciousexperience with its qualitative content arise from bare difference? Bare differ-ences within cellular automata are a surprisingly fruitful ground for the emer-

gence of an incredibly large number of kinds of things Life itself can exhibit

phenomena of indefinite complexity For instance, because we already know that

Life may contain self-replicating phenomena, we cannot rule out that it could hibit some kind of genuine life Because Life supports the existence of objects

ex-that dynamically evolve, it is at least an epistemic possibility ex-that these entitiesmight eventually lead to the existence of animate objects We also have to hold it